diff --git a/cmd/tsconnect/wasm/wasm_js.go b/cmd/tsconnect/wasm/wasm_js.go
index 054bcbea2..1c1028b22 100644
--- a/cmd/tsconnect/wasm/wasm_js.go
+++ b/cmd/tsconnect/wasm/wasm_js.go
@@ -873,6 +873,11 @@ func (i *jsIPN) listen(network, addr string) js.Value {
 			if n == "tcp" {
 				n = "tcp4"
 			}
+			// netstack.ListenTCP requires a full host:port; normalise the
+			// standard net.Listen form ":port" that omits the host.
+			if strings.HasPrefix(addr, ":") {
+				addr = "0.0.0.0" + addr
+			}
 			ln, err := i.ns.ListenTCP(n, addr)
 			if err != nil {
 				return nil, err